You can purchase a dog clicker for about $3 on Amazon.
If you don’t own a dog, this is not a useful piece of information. I don’t own a dog, and the first time I heard the phrase dog clicker, I thought—I think understandably—that it was some sort of remote control.
If you don’t own a dog, but you have seen one of the films in the Jurassic Park reboot, then you have seen a dog clicker in action: It is the device Chris Pratt holds in his hand as he tries to convince his pet dinosaur not to eat him. It is essentially a piece of plastic that makes a clicking sound when a button is depressed.