You need to have a camera to do this. Move your face the background will move. When you get close to the camera the Kerbal will get bigger. Note: The sensing is not perfect What improvements do you want to see put it in the comments below!
Thanks to: @Pedro67855 for the Kerbal art If you want his Kerbal art you can get it here: https://scratch.mit.edu/projects/1013504601/ And thanks to: @randalpik for the original project, you check that out here: https://scratch.mit.edu/projects/276507