A hearty combination of "Machine Vision" and "Bluetooth HID" function yields this "Office Tripwire" device.
How it works:
Essentially, it works by letting the OpenMV device to constantly comparing the current frame captured with the last frame, if the difference is greater than a set threshold, then a signal will be generate on a GPIO pin to alert the Ameba (AMB23 RTL8722DM), which then functions as a bluetooth keyboard and send a "Alt + Tab" keystroke over bluetooth to the connected device whose primary program will be switch to the next program.
The same function can be achieved by just using a PIR sensor. However, with OpenMV, you may add in a hint of AI by enabling the Face Recognition feature on OpenMV, then this device could potentially only triggers when a face that is not on the whitelist is detected, making it actually useful and fun.