In Episode 2 of the Windows 10 Narrator Series, I identify the two Narrator keys (Caps Lock or Insert) that are used to start a Narrator command.

I then move on to demonstrate the Input Learning mode accessed via Caps Locs plus 1 that allows the user to explore the keyboard, Narrator commands, and the touch screen (such as on a Surface pro) without the keys, Narrator commands or touch's on the screen being acted upon.

To exit Input Learning mode, Caps Lock+1 twice.

As I point out in the demo, if you want to use the Caps Lock function, press it twice to turn it on and again twice to turn it off.