If you want to know when System Services is using your location, then you can adjust your iPhone settings in iOS 9 to display the arrow icon for those location usages as well.
Enable the Status Bar Symbol When System Services Uses Your Location
The steps in this article were performed on an iPhone 6 Plus, in iOS 9. Enabling this option will result in the arrow icon being displayed at the top of your screen on a much more frequent basis. When this option is not enabled, the Location Services symbol will only be displayed when your location is being used by something other than a system service.
Now whenever a system service uses your location, whether for Wi-Fi networking, cell network search, frequent locations, or any of the other options listed on this screen, the GPS arrow will be displayed at the top of the screen. If you find that your iPhone is using your location too often, then you may decide to turn it off completely. This can help to improve your battery life. You can learn how to turn off iPhone Location Services if you want to see how your device usage is when it doesn’t know where you are. After receiving his Bachelor’s and Master’s degrees in Computer Science he spent several years working in IT management for small businesses. However, he now works full time writing content online and creating websites. His main writing topics include iPhones, Microsoft Office, Google Apps, Android, and Photoshop, but he has also written about many other tech topics as well. Read his full bio here.