Unless someone who worked there previously switched the black and white, or used a neutral to carry current without re identifying it. OP needs a proximity tester so they can verify first.
Others have answered the basic question so here's my specific recommendation and why...
I've had quite a few over the years stashed in the various bags, but usually Fluke with a couple Klien ones. Recently broke my everyday one (got run over by a baker) and picked up a Fluke 2AC off Amazon (tip - If you need it sooner go hit up any local electrical supply outlet like Platt etc, not HD/Lowes) https://www.amazon.com/Fluke-2AC-Alert-Voltage-Tester/dp/B004I9J4DI
The thing I love about these is no on/off, very simple & fast - they just light up when it detects. But the new one has a test button that lights up to verify it's working first. I never realized how handy that is, and otherwise it's the same old super-simple tech. A+ go get one
thank you. Would this work as well?
Why the hell would you use a multimeter? You don't need to know what voltage it's at you just need to know if there is current passing through. A contact less voltage tester would do the job just fine.