All objects obey this rule, and this principle has been known for a couple hundred years. This is called mutual capacitance, and this form of capacitance is much more important and usually more dominant than simple 'free-space' capacitance. Even a football flying in the air has a mutual capacitance with respect to the earth, as do the earth and the moon with respect to each other. The amount of capacitance between two objects decreases with distance and increases with the sizes of the two objects. It then looks at very small changes in the measured signal from that point on, caused by nearby objects.
Capacitance is affected by what the object is made of.
For example, a metal object is vastly better at storing charge than an identically shaped one made of plastic. And some plastics are better than other plastics. Also, what is between two objects strongly affects the amount of mutual capacitance between them. For example, when two metal objects are separated by a layer of plastic, there will be more mutual capacitance than if the two are separated by a similar spacing of air. This variation is expressed in physics terms as the dielectric constant of a material.