Hey there! Nice to meet you!
Based on your description, the hacker was able to remove the account's primary email address/security info and replace it with the hacker's email address, which is why you received the error that your account is not recognized when signing in.
Since the security info has been replaced by the hacker, I'm afraid there is no other working method to recover the Microsoft account, and Microsoft Support cannot help either.
Thank you for your understanding.
Best regards,
Darhyl