Hey Bombadillo_7,
If you’re syncing your Contacts from iCloud, we recommend following the steps here: If you think your Apple ID has been compromised - Apple Support
If you’re using your email account(s) for Contacts, we recommend changing your email password(s). You’ll need to find the steps to do this on your email provider’s site. Be sure that the password you change it/them to is a strong password that’s not easily guessed.
You may also want to share this article to those who have received these emails that appear to be from you email account: Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support
Feel free to get back to us with any questions or problems you may have.
All the best.