Q: new credit card hacked on macbook

You're account having been hacked is not in anyway related to a computer virus.

If you have not already done so, change your Apple ID password >  Apple ID: Changing your password

Contact your bank to report any unauthorized transactions.

For the time being, change your payment method to None >  Mac App Store: Changing your account information

Why can’t I select None when I edit my payment information?

You posted this in the Mac App Store forum... were purchases made using your Apple ID in the Mac App Store? If so, see Carolyn's response for starters. Also, you can contact Apple to dispute charges on your Apple ID. Don't contact the credit card company unless there are also transactions made with the card directly, rather than through your Apple ID. If all purchases went through your Apple ID, that was hacked, but your credit card number was not obtained.

If the choice of forum was erroneous, and you've had a general credit card breach, this is extremely unlikely to be due to malware on your Mac. Your Mac is pretty secure against real malware at this time, so unless someone malicious has had physical access to your Mac and installed a keylogger or something, I'd have to say it's almost impossible. Credit cards get breached all the time without malware being involved.