How do I add detail to polygons

I have modeled a tripod head from war of the worlds but the detail is no close to the reference I am looking at. The bump on the for head area is supposed to have more detail on it. Should I sculpt it or model it into the polygons with extrude. Here is my reference:

Here is my model:

Also the middle light is lacking detail too if you compare my model to it. How should I go about adding detail.