That would only pick up whatever frequency your antenna \coil was tuned or sympathetic to.Back in the 80's, didn't nerds build something with a magnet, speaker & battery to pick up whatever feedback/frequency? I can't remember what/where/how-
Assuming you're looking for a cellular signal from a tracking device there's like a dozen bands, and all of those have thousands of possible frequencies and they're constantly changing so everything can coexist in the band.
So you need some sort of broad spectrum monitoring ability and a software defined radio it's the cheapest\best option.