If you think your phone is hacked, or has a tracker and you can not afford to get a new one AND you don't plan to press criminal charges (if you want to / need to do NOT wipe the phone, get it to cops or forensics people ASAP).
Honest best thing - buy a new phone. if you can't then try the following.
Most partner hacking I have heard of is app based, using that assumption:
- backup images and contacts
- make sure you are on your OWN phone plan
- reformat SD storage if it has a card
- factory restore the device
- turn off the device as often as possible to avoid apps geo-tagging you and giving away your location
- some things can track a turned off phone
- Did you know every image you take and post, and many social media sites, give away GPS coordinates you can't see but others can use when you post?
- you can try a cell phone blocking wallet/purse but the quality and efficacy varies
- only re-install apps you use and know what they are
- please don't root your phone