My iPhone has been hacked

I’ve been told that iPhones can’t be hacked, but I know for sure that unfortunately mine is. My phone acts completely strange and does things on its own…takes pictures, pictures show up that I didn’t take, websites that I didn’t go to are open, my text conversations open on their own, I can’t move the cursor around while typing a text, when sending a text my phone glitches, and only glitches when sending texts, emails get opened that I didn’t open, texts get deleted that I didn’t delete, and my phone does lots more. My question is…..how do I get the hacker off my phone without spending lots of money to do it? I talked to a company that specializes in finding and removing the hacker but it’s going to be really expensive. Factory resetting doesn’t help, I’ve tried it.

[Re-Titled by Moderator]