I've got a screwdriver that incorporates a non-contact AC current sensor. Mine is a Gardner Bender SDT-354 [1] that I think I bought at Home Depot or Lowe's.
When the current sensor is turned on if you bring the tip of the screwdriver near a live AC wire an LED in the handle starts rapidly blinking and a beeper starts rapidly beeping.
It once may have saved me from a nasty shock. I have an outdoor light over the garage that is controlled by a light sensor, and the light sensor was going bad. It would turn the light on when it got dark but not turn it off in the morning. So I'd flip the breaker for that light off and then back on every morning.
When morning when I went to open the electrical panel in the garage I got a shock from the panel door. I went in and got the current sensing screwdriver and went back to the garage to see if I could get an idea of what the heck was going on.
As soon as I stepped into the garage the screwdriver started blinking and beeping. A little experimenting showed it would go off anywhere in the front half of the garage that was more than about a meter above the floor.
It turned out that the metal garage doors and the metal rails their rollers rolled on and the metal tracks the garage door openers pulled the doors on were all connected to live AC.
I got the fuck out of there and called an electrician.
What happened was that in the shed next to the garage that houses my well some critter had chewed through some of the insulation on some of the wiring for powering the well pump. I'm not sure how but that somehow made the cover and door of the electrical panel and all those metal parts of my garage door system electrified, but without stopping the well pump from receiving power.
[1] https://www.amazon.com/Circuit-Alert-Blade-Screw-Driver/dp/B...