This 1-Command creation adds crawling, climbing fences, and climing on iron bars from below, as well as High-Jumping.
To Crouch, Look straight down, crouch and move.
To Climb up a fence just walk up to it and jump.
To Climb across Iron Bars, just walk under them.
To High-Jump, Look up, Crouch, Walk, and Spam Jump until you see Jump Boost particles. The Jump boost will last 3 seconds.
Quite another Long command. (Using Mr. Garreto's Command Combiner)
/summon FallingSand ~ ~1 ~ {Block:redstone_block,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:fill ~ ~ ~1 ~ ~-30 ~1 redstone_block},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~ ~3 ~1 stone},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~ ~4 ~ command_block 0 replace {Command:fill ~ ~2 ~ ~ ~-33 ~1 air}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~3 ~27 ~ {Block:command_block,Time:1,TileEntityData:{Command:fill ~ ~ ~-1 ~6 ~ ~1 log 13}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/playsound portal.travel @a},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/tellraw @p ["",{"text":"Special Moving mod in vanilla minecraft ","color":"blue","hoverEvent":{"action":"show_text","value":{"text":"","extra":[{"text":""},{"text":"Sort of.","color":"blue"}]}}},{"text":" Made By","color":"dark_gray"},{"text":" Barf Head ","color":"gold","bold":"true","clickEvent":{"action":"open_url","value":"www.youtube.com/c/barfhead"},"hoverEvent":{"action":"show_text","value":{"text":"","extra":[{"text":"www.youtube.com/c/barfhead","color":"gold"}]}}},{"text":" Generated using Mr Garretos Command Combiner","color":"dark_gray","bold":"false"}]},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard objectives add jump stat.jump},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard objectives add shift stat.crouchOneCm},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard objectives add crawl dummy},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard objectives add timer1 dummy},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard objectives add timer dummy},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~4 ~ ~-1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:scoreboard players remove @a[score_timer1_min=10,score_jump_min=1] jump 1},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players add @a[score_crawl_min=1] timer 1},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ fill ~-4 ~-4 ~-4 ~4 ~4 ~4 air 0 replace barrier},Time:1,}}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~5 ~ ~-1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players set @a shift 0},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_timer_min=3,score_timer=3] ~ ~ ~ detect ~.1 ~1 ~ air 0 tp @p ~.01 ~ ~},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ spruce_fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~6 ~ ~-1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/effect @a[score_jump_min=3] 8 3 1 false},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_timer_min=7,score_timer=7] ~ ~ ~ detect ~-.1 ~1 ~ air 0 tp @p ~-.01 ~ ~},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ nether_brick_fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~7 ~ ~-1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players set @a[score_crawl=0] timer 0},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ dark_oak_fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~8 ~ ~-1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_crawl_min=1] ~ ~ ~ fill ~1 ~ ~1 ~-1 ~-1 ~-1 barrier 0 replace air},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_shift_min=1,rx=90,rxm=90] ~ ~ ~ execute @p ~ ~ ~ detect ~ ~ ~ air 0 tp @p ~ ~-.1 ~},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~9 ~ ~-1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players add @a[score_shift_min=1,rx=-90,ryx=-90] timer1 1},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~2 ~ iron_bars 0 fill ~ ~-1 ~ ~ ~-1 ~ barrier 0 replace air},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~4 ~ ~1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players set @a[rxm=-55,rx=90,score_shift=0] jump 0},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_timer_min=1,score_timer=1] ~ ~ ~ detect ~ ~1 ~.1 air 0 tp @p ~ ~ ~.01},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~5 ~ ~1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players set @a[score_timer1_min=10] timer1 0},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_timer_min=5,score_timer=5] ~ ~ ~ detect ~ ~1 ~-.1 air 0 tp @p ~ ~ ~-.01},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ birch_fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~6 ~ ~1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players set @a[score_timer_min=8] timer 0},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ jungle_fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~7 ~ ~1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/effect @a[score_crawl_min=1] 2 1 3 true},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~-.5 ~ acacia_fence 0 fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~8 ~ ~1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ fill ~ ~ ~ ~ ~ ~ air 0 replace barrier},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/scoreboard players set @a[score_shift_min=1,rx=90,rxm=90] crawl 1},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:summon FallingSand ~9 ~ ~1 {Block:log,Data:13,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a[score_shift_min=1,rx=-90,ryx=-55] ~ ~ ~ fill ~ ~2 ~ ~ ~2 ~ barrier 0 replace air},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:/execute @a ~ ~ ~ detect ~ ~ ~ air 0 /scoreboard players set @a crawl 0},Time:1,}}}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:gamerule commandBlockOutput false},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"fill ~3 ~-4 ~ ~9 ~-2 ~ redstone_block"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"setblock ~3 ~-3 ~-1 command_block 0 replace {Command:fill ~ ~ ~1 ~6 ~2 ~1 stone 0 replace redstone_block}"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"setblock ~3 ~-2 ~1 command_block 0 replace {Command:fill ~ ~ ~-1 ~6 ~2 ~-1 redstone_block 0 replace stone}"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:fill ~2 ~-1 ~-2 ~10 ~1 ~2 iron_bars 0 replace log 13},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:fill ~3 ~ ~-1 ~9 ~5 ~1 air 0 replace log 13},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:fill ~2 ~ ~-2 ~10 ~4 ~2 log 13},Time:1,Riding:{id:"FallingSand",Block:stone,Time:1}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}