1. An image capturing apparatus comprising: an image capturing unit configured to capture an image of a subject; an image capturing control unit configured to perform image capturing using a first pixel group of the image capturing unit during a first exposure time to obtain a high-exposure image, perform image capturing using a second pixel group of the image capturing unit during a second exposure time which is shorter than the first exposure time to obtain a first low-exposure image, and perform image capturing using the second pixel group during a third exposure time which is shorter than the first exposure time to obtain a second low-exposure image, the second and third exposure times at least partially overlapping the first exposure time; and a detection unit configured to compare the first low-exposure image with the second low-exposure image to detect a motion of the subject.