Unlock your Mac and approve tasks with Apple Watch
When you’re wearing your Apple Watch, you can use it to automatically unlock your Mac mini and approve authentication tasks—such as entering passwords, unlocking notes and settings, and authorizing installations—without having to type a password. These features use strong encryption to provide secure communication between your Apple Watch and Mac mini.
To use the Auto Unlock and Approve with Apple Watch features:
Make sure your Apple Watch is unlocked and running watchOS 3 or later to automatically unlock your Mac; approving authentication requests requires watchOS 6 or later.
Turn on two-factor authentication (see below).
Set up two-factor authentication for your Apple ID. To turn on two-factor authentication, go to Apple menu 
> System Settings, click your Apple ID in the sidebar, click Password & Security, then select Set Up Two-Factor Authentication. See the Apple Support article Two-factor authentication for Apple ID
Make sure “Disable automatic login” is also selected. (You won’t see this option if you’re using FileVault, but you can still use the “Auto Unlock” and “Approve with Apple Watch” features. For information about FileVault, see Encrypt Mac data with FileVault in the macOS User Guide.)
Set up Auto Unlock. Sign in on all your devices with the same Apple ID, then open System Settings on your Mac mini. Click Touch ID & Password in the sidebar, then turn on the unlock settings for Apple Watch.
Note: These features work only when your Apple Watch is authenticated with a passcode. You authenticate your Apple Watch each time you put it on, so no extra steps are necessary after you enter your passcode.
Skip the sign-in. Walk up to your sleeping Mac mini wearing your authenticated Apple Watch on your wrist, and press a key to wake your Mac. Apple Watch unlocks your Mac so you can get right to work.
Approve with Apple Watch. If you’re prompted for a password, double-click the side button on your Apple Watch to authenticate your password on your Mac. You can view your passwords in Safari, approve app installations, unlock a locked note, and more (requires watchOS 6).
Learn more. See Unlock your Mac and approve requests with Apple Watch in the macOS User Guide.