What to do if my Apple Account is being hacked?

You will need to provide some details on how you came to that conclusion.

• You can review devices that are logged into your account by going to Settings > [name on top], and scroll to the bottom to see the list of devices logged in. If any of them are not yours, then they can be removed and you will want to follow up with changing your password.
• Accounts are compromised all the time when users inadvertently respond to phishing emails/messages. The solution is simple, do not call a number or click a link in any email or message and provide personal information.

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

• If you feel your Apple Account has been compromised, then follow the steps here. Any account can be compromised depending on what information has been given out. Your device can only be compromised if they have physical access to it with your Passcode. If your phone is mirroring data from an account that has been compromised, then you will see those changes on a compromised account, but it does not mean they have access to your phone.

If you think your Apple Account has been compromised - Apple Support