Many ordinary objects could be turned into weapons or otherwise misused by people with ingenuity and nothing to lose. That's why, as we've noted in the past, there's an entire industry that produces ordinary household and office products for prison environments.
This includes computers. Zephray Wenting purchased a prison laptop named the Justice Tech Solutions Securebook 5 on eBay. The laptop is encased in a transparent plastic shell. It has no hard drive or USB port. When turned on, the laptop asks for a password. Wenting opened the case and partially disassembled the machine, but has had no luck so far hacking the password.
You can read a complete exploration on Twitter or a detailed and informed summary on Hack-A-Day.