Five Best Apps that turn your phone into an extension for your PC

Phone as Audio Source (mic/headphones)

Phone as Video Source (Webcam / Security Cam)

Phone as Input (keyboard and mouse)

Phone as a Extra Display (monitor)

Phone as controller for another phone (or controller from a browser)

Bonus Round:

Phone as a server!

Phone as a pentest tool

aka… install kali linux and termux linux console