I need some advice on the best way to discreetly know when my boss is coming up behind me, so I can quickly switch away from Reddit. I'm pretty handy with a soldering iron and know a bit of Python. I'm thinking about using a small PIR or mmwave sensor aimed behind me, but I want it to be undetectable, or at least disguised in a 3D printed figure that looks like an eye or something similar. I'd prefer an instant notification on my PC, but I'm worried about delays with WiFi or Bluetooth. The next best option would be wiring it directly to a small indicator light that I can place inconspicuously near my monitors. Any thoughts or suggestions?
3 Answers
Maybe consider a clever setup like a mirror on your monitor, positioned off to the side where it's less noticeable. Just use some adhesive velcro to keep it in place—remove it when you’re away from your desk. And if anyone questions it, you could always explain that it helps with your anxiety or a heart condition—it’s a simple coverup!
You might want to consider a 10GHz radar module. I’ve used one that detects movement and can be wired to a vibratory motor placed on your chair—perfect for notifying you without making noise. I powered mine with a 9V battery. Just be aware that it can be overly sensitive. If you position it facing downward from the chair’s leg, it should only activate when someone is right behind you, and it’s pretty discreet.
That’s a cool idea! A vibrating chair setup definitely adds an element of sneakiness. Even though I simplified things in my original post, I think placing the sensor maybe a bit higher could help—you know, to spot any movement straight in front of me.
Another option is using a radar presence sensor with an Arduino like the ESP32. If you set up two of them for direct Bluetooth or WiFi communication, you’ll get almost instant alerting—and it can be entirely silent. I’ve created automated cases that shut when it detects an alert. Pretty neat stuff!
That sounds promising! Can you share any tutorials or additional details on how you built that? I’d love to check it out.

That’s a smart idea! I’ve got some glass on top of my cubicle, which reflects everything, so a positioning adjustment for the sensor might be just what I need.