MacID for iOS is a pretty fascinating app. It lets you unlock your Mac with your fingerprint or a passcode. It also lets you control your Mac’s audio and authorize with Touch ID for tasks that require admin credentials. The app is now compatible with the Apple Watch. As you can see in the below video, it is now possible to use an Apple Watch to unlock your Mac or control your music.
Let’s not forget that with MacID, your password never leaves your Mac. Your fingerprint data or passcode is not disclosed to the app. The MacID app is pretty cheap too!