The look-controls component:
The look-controls component is usually used alongside the camera component.
<a-entity camera look-controls></a-entity>
If you want to create your own component for look controls, you will have to copy and paste the HMD-tracking bits into your component. In the future, we may have a system for people to more easily create their controls.
For this you need to add a cursor component to your camera
<a-scene> <a-camera> <a-cursor></a-cursor> <!-- Or <a-entity cursor></a-entity> --> </a-camera> </a-scene>
More information you could find on the cursor (component) topic.