You can find the camera driver on the raspberry PI, but input raspistil-o image.jpg on the raspberry PI terminal, and output the following error:

mmal: Cannot read camera info, keeping the defaults for OV5647
mmal: mmal_vc_component_create: failed to create component 'vc.ril.camera' (1:ENOMEM)
mmal: mmal_component_create_core: could not create component 'vc.ril.camera' (1)
mmal: Failed to create camera component
mmal: main: Failed to create camera component
mmal: Camera is not detected. Please check carefully the camera module is installed correctly

The reason for this is that the camera used is a USB camera, while the Raspistill command only works with the CSI camera. For the USB camera, you can access it by calling FSWEbCAM.
enter sudo apt-get install fswebcam to install fswebcam on raspberry PI terminal. Enter sudo fswebcam image.jpg for the photo test. You can use this method by entering fswebcam-h .