The microchips just have registration details, owners name, contact details etc, so that if a dog or cat gets picked up and taken to a shelter/refuge or the pound, the workers there can scan it, and call the owner to let them know its turned up.
Although it would be possible to have a gps/tracker chip in an animal. These are used for wildlife monitoring animal populations - usually rare species or those with small populations. I did see something where they used a handheld antenna to receive signals from chipped animals. They didn't give exact locations, but you could tell which direction an animal was, and guess its distance based on the strength of the signal.