It’s unlikely you’ve been hacked. Given the age of your computer, I wouldn’t be surprised if the only storage onboard the machine is a 3gbps SATA HDD. I would strongly recommend upgrading to a more current laptop, and preferably an upgradeable type like those from Framework, as the ability to easily and quickly replace individual parts as they fail for cheap by yourself will doubtless prove invaluable.

Anything that renders the platters not intact. A drill press is commonly used but you could just throw it at the ground and they’d shatter. Alternatively, you could shoot it with whatever caliber you have on hand.