How do I use the Dynamic Lock feature in the Windows 10 Creators Update?
Another ease-of-use addition available in the Windows 10 Creators Update is Dynamic Lock, which uses a Bluetooth connection between your phone and your PC to automatically lock your PC when you (and your phone) move out of range.
Your PC will stay unlocked for 30 seconds after it senses you've left the Bluetooth range. It doesn't unlock your PC; if you go out of range and Dynamic Lock shuts things down, you have to sign in with your password, PIN, or Windows Hello.
Full story from the WindowsCentral blog...