Hold up something red like a bottle cap and you should see a 3d sphere following it around.
When your up to it, use arrows and mouse to move around and it should still track to the plane showing your webcam.
https://www.babylonjs-playground.com/#YGKM4#1
As it identifies red above a certain threshold make sure there are no other red objects in the environment (like a t-shirt) or tracking may get weird.
Let me know if it works since I've only tried it at home