Unauthorized access to iCloud and Apple Account on iPhone

I need help. Someone is in complete control of my phone. I guess I got my iCloud information or maybe my Apple ID I don’t know what to do every time I change my password they get it. They’re getting everything on my phone. They can even mess with my screen, they can even control my maps. They see everywhere I go

[Re-Titled by Moderator]

Original Title: Someone has all of my iCloud information and when I changed my passwords, they’re getting them. I don’t know what to do.