There are many different programs and applications that allow you to track the location of a device and/or a person. I often read on the portal https://androidcellphonetracker.com/ reviews of new software that helps to do this, instructions on how it can be quietly connected and used for espionage. I know that tracking apps like this are very popular for those who put hard parental controls on their kids' smartphones. But it can also be used for many other purposes too.