If you want to make a *really* secure seal — nuclear /
highest-level attacker type security — design a device to precisely register a sheet of glass in front of whatever you don’t want disturbed (like a safe dial), and a laser some distance away, perhaps shining down at a 45-degree angle. Have the laser beam spread to cover the entire sheet of glass, shining through it onto the object.
Get a supply of high-resolution thick-film emulsion holographic plates. Put one into the holder, and expose using the laser. Develop, and keep the plate in your pocket. When you come back, put the plate into the holder. If the object was not touched, you’ll see even zebra stripes across the whole surface. If anything was disturbed, the zebra stripes over that area will be way, way off.
In order for an adversary to bypass this, they would need to precisely re-position the disturbed object to within a ~half wavelength of its original position, or some hundred nanometers. Yes, nanometers…
As for plates, try the Slavich PFG-03M:
Using an average red diode laser in the below described configuration should give you a usable depth of 2-3cm (about an inch). (Objects further away from the glass plate won’t be visible.) A He-Ne laser, properly warmed up, will give you a few inches, a Coherent C315M several meters.