Get this--you can use a stud finder to detect microchips in dogs! I bet you are skeptical, I was too. I asked my person to check to see if our stud finder could find my microchip. It worked!
My microchip has anti-migration technology, so it will always be on my back. But if you are looking for your microchip that may have moved...just have your person grab the stud finder!
On a related note, I am really glad my person decided to get me my own microchip last year...that way if I ever get lost, I know I will find my way home. Tell your person to ask the vet about getting your own microchip, it doesn't cost much money, but it buys a lot of peace of mind.