Electrostatics: an electron within a cavity in a conductor

We all know that putting some charge within a cavity in a conductor, makes its free electrons move in a way that those charges become electrically isolated from the outside world. But what happens if only one electron is put? If that’s possible, what is the configuration of the induced charge on the inner surface (which indeed consists of electrons, elementary particles having elementary charges) and if that’s not possible, why? (Keep in mind that the induced charge is equal and opposite to the charge inside. You may also assume the conductor and its cavity as two concentric spheres and our electron at the center for the sake of simplicity.)
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