How can I tell if my Apple account has been hacked

Unless something has changed in your account, there isn't a way to tell.

Link to contact Apple Support in the article.

Apple ID has been compromised.      

Security and your Apple ID.      

What Device Are You On?,

If You Are On A Mac, Then I Can Suggest An Anti-Malware App That Can Properly Remove Malware From Your Device,

Its Called Malwarebytes