Everytime your phone is been tracked, the gps icon will show up in your status bar.
The only way that person can track you is if you have a app installed in your device. Or your Google account have been compromised.
Go to your setting and find your apps section.
Make sure you know all the apps. if you dont remember or use or suspect an app remove it.
Some apps can be hidden so make sure you go to the Play Store and take a look at "My Apps"and do the same. delete any suspicion app.
Lastly and most important make sure you change your Google Account password to remove any remote access.