Your dog has learned over its life about linking objects with people and behaviors. The I Rex spent its entire life inside a cage and successfully linked the implant it received as a baby to humans being able to track it on the first guess before the humans had even found it. It then proceeded to cut the tracker out of itself with its claws and use it to set up an ambush. That's a level of deductive reasoning beyond what could be expected for a human who grew up in those circumstances.
Animals link objects with observed phenomena, not just humans or pack-mates e.g. they can learn how to operate door handles as well. It's true that the movie's implication that I-rex set up an ambush is a little far-fetched.
My fan theory though - that tracker is larger and bigger round than a smartwatch (see below). It was probably implanted when I-rex was a young adult*, and is possibly big enough to feel uncomfortable. Like Blue and my dog, who both hate collars, I-rex clawed it out in a fit of freedom-inspired spite. But (like my dog) it then kept the item, unsure whether to abandon it or not. That's when the capture team found it - so it was a matter of chance, not necessarily a premeditated ambush**.
*a preteen T-rex is about the size of a large dog. An implant that size would have to be inserted when I-rex was at least the size of an SUV. Alternatively, if progressively larger implants were inserted since it was a baby (a little unlikely) then it would have remembered the frequent operations**.
**in which case IF one accepts that the I-rex is smart enough to link implant with humans e.g. by repeated insertions, then even for a dog it would be intuitive to linger a little and see if humans (prey? enemies?) come to get the removed implant.
of course this is all just fun fan theorycrafting ;D
