Steps:
1. Open your phone call Dialer.
2. type *#0*#
3. Automatically open a Grid View with several testing options like Mega Camera, Vibration, Dimming, Sensor,Touch, Sleep, Speaker, Receiver, Sub Key, Front Camera, Led, Low Frequency etc.
Here,I upload a video, how to achieve this. I Share my physical android mobile Samsung S3 screen with my computer.