Why is my mouse cursor is moving on its own

I've occasionally had this problem on my Win10 laptop, I can't say what specifically was the fix but I did several things. Make sure your mouse drivers are up to date. Next, launch the troubleshooter from the start button and let it do its thing for the mouse. Then unplug the mouse if wired, or disconnect if Bluetooth, then reinsert and reinitialize. Again, if Bluetooth, try running the troubleshooter for that. If the mouse has batteries, try pulling them out for 10 to 15 seconds to reset that. Finally, as a last resort, I suspect it's not a mechanical problem but you may want to disassemble. If optical, make sure it's clean, for rollers check the mechanics for smooth operation, etc.

If any of this works for you, leave a note as to which it was.