There is no guaranteed way to sneak out with Find My iPhone, as the feature is designed to track the location of a lost or stolen device. However, there are a few things you can do to try and avoid detection:
-Turn off Find My iPhone before leaving the house
-Make sure your device is not connected to Wi-Fi or cellular data
-Avoid using location services
-If you must use location services, use a fake location
-Turn off all notifications on your device
-Do not use any apps that require your location