Compound eyes detect motion, and simple eyes detect light.
or
The compound eyes are used to "see". The simple eyes are used to detect light intensity.
The simple eyes also called ocelli are only used to detect light intensity and not for seeing.
Compound Eyes are a group of thousands of participates that capture light, color and brightness.
The compound eye of a grasshopper detects movement and helps the grasshopper to see.
compound
for seeing