My iPhone or Apple ID is cloaned

all my account activity is being monitored by a hacker who has created a fake loan of my account every app that I’ve downloaded this then re-download it again to another device. How do I find out what the device is where it’s at because it has it looks like my iPhone anytime I change the password and account you knows it and how much it happened on the screen doesn’t happen it’ll be racing when I tap missing my passwords app. How can I that? Was you doing it?