The most reliable way to catch those sneaky mylings is to pay close attention to the timing of sounds during hunts. When a regular ghost starts hunting, you'll hear their footsteps from quite far away, around 20 meters out, but mylings are much sneakier with just a 12-meter sound range. Here's what makes it interesting: place your flashlight somewhere visible and watch for the flicker which happens at 10 meters, if you suddenly start hearing footsteps right when your electronics go crazy, that's probably your myling since normal ghosts will make noise well before that point.

Those random ambient noises like creaks and bumps are pretty different from actual ghost movement, since they don't follow any real pattern and happen totally random during the hunt. Something worth noting is that while mylings are quiet during hunts, they're actually quite noisy during regular investigation throwing stuff around and touching doors just like other ghosts would. If you want to be extra sure, try hiding just beyond that 12-meter mark from the ghost room and pay attention to when you start hearing things compared to when your equipment starts going nuts - with regular ghosts you'll definitely hear them coming before seeing any electronic interference.