What you mean. How they use wifi to track movements around?
Discussion
Yeah I've not researched it and people are meming about it already and either already know or are pretending to know what it is.
What I would do is simply use signal strength of a device you hold as a rough proxy, especially if you can triangulate it.
This is the principle. Checking variation of dielectric constant of moving materials and somehow with a huge amount of data processing extract approximate position of some moving objects.
Easy? Not!
https://hackaday.com/2020/10/22/affordable-ground-penetrating-radar/
No that's the principle behind the noise they discovered under the great pyramids.
It's the same stuff. Radar imaging. Different frequencies, different resolution.