In the past, i have because my mom would routinely snoop to see if I was still talking to the boy she forbade me to date (I was, and i got more clever about hiding it). The only way she let me keep a phone was if I didn't put a pass code on it.

Fast forward to a couple of years after moving out of her house and in an emotionally abusive relationship. That dude ended up putting spyware on my phone (without my knowledge) because.. well, idk, control i guess? I was messaging a close guy friend of mine, and my boyfriend fucking blew up at me, which is when I realized he had been spying on me. I wasn't flirting with my guy friend or anything (we really didn't have a relationship like that at all). he was just messaging me late at night because his step dad was abusive to him and I was helping him through that tough time. My boyfriend did not allow me to message another male after 9p.

Those had me paranoid, but can't say I'm paranoid anymore. I'm married to a guy I trust, and he has my phone password info and I have his. I don't snoop in his phone and I trust that he isn't snooping in mine. Not like I have anything juicy in here, anyway.

But yeah, if you're feeling paranoid without someone having previously violated your trust, it could be because you are doing things on your phone that you consider to be very private/embarrassing/nefarious? If so, that kinda makes sense I think. If that's not the case, then respectfully, it might be good to see a mental health professional.. life becomes a lot less stressful without worrying about shit like that.