There are 3 agencies: Transunion, Equifax, and Experian.
I froze my credit with all three more than 4 years ago. I just had to unlock my credit freeze with Transunion a month ago, and (s)surprise!(/s) my online account doesn't work anymore. But calling was easy enough to get around it.
That and periodically checking you credit report is all that I would suggest. Credit Karma is always trying to get me to log in, so I'm sure if something wild showed up, I'd get a notification in my email quickly.
Having someone access your money accounts and having someone use your credit are very different situations. You can dispute credit situations, and file police reports if someone takes a loan out in your name, and you're very rarely out any money. But accessing your accounts and moving money around could cost you dearly. I use 2 factor authentication and check accounts frequently to prevent unauthorized and a undetected access.