Hacker has remote access to my IPhone 14, for the past 9 months

Hey all, a hacker has been changing the settings of my phone, pausing and playing my videos and my music for the past 9 months! Reformatting doesn’t help and neither did buying a new android phone instead! Would logging into mdm and then removing it help me at all?? Or does that not really disable the ability of the phone to be remotely accessed? Help.