Yes, flick a switch
If you've allready got one, you should either read the user guide or look at the on/off switch, which according to the page you linked to (under "Product Features") has got a 4 Position Switch: ON/OFF/OS Sensor/NightLight.
Set it to Nightlight and it will light when movement is detected - I assume that's what you meant, because if you really want a light detector
, you have bought a paperweight.
This is a movement detector
reacting to body heat moving around in front of it.