There is a simple intro to the A2D chip https://www.raspberrypi-spy.co.uk/2013/ ... n-mcp3008/
using different sensors but it does cover the physical connection to the Pi and the basic software needs as a starting point. This one is also a neat step by step guide https://electronicshobbyists.com/raspbe ... terfacing/
As for the joystick - more details will be needed for anyone to help you.
I’ve asked the mods to pop this thread into the assistive technology forum.