To run a VR application without loading your mobile device into a headset, you must enable Developer Mode.
It is often convenient during development to run VR applications without needing to insert your device into the Gear VR headset, which can be a time-consuming process during development.
When Developer Mode is enabled, any Oculus application on your mobile device will launch with distortion and stereoscopic rendering applied without inserting the device into a headset. Devices in Developer Mode implement limited orientation tracking using phone sensors. Orientation tracking may be disabled with the appropriate setting to System Properties or Local Preferences (see Android System Properties and Local Preferences for details).