Linux system administrator and software engineer Michael Altfield designed a kill-cord called BusKill that can trigger a specific action when it gets disconnected from the laptop. BusKill is a cable with a USB drive at one end that attaches to your body and your laptop at the other. When the drive disconnects, it acts on a predefined ‘udev’ event, which can be anything from locking the computer, shutting it down, or wiping data on it. Altfield spent about $20 to build BusKill but this depends on the quality of the items you choose.
Source: https://www.bleepingcomputer.com/news/security/buskill-cable-starts-a-self-destruct-routine-on-stolen-laptops/