A control apparatus has one or more built-in functions that are selectively usable. The control apparatus includes a first communication unit conducting a first communication and a second communication unit conducting a second communication, a built-in function unit configured to execute the built-in function, and at least one control circuit. The control circuit determines which of the built-in functions is selected, determines whether there is an external device to execute an external function related to the selected built-in function based on the first communication, controls an icon display to present to a user that the selected built-in function is also executable by the external device, and causes the second communication unit to communicate with the external device through a second communication to execute the external function when the external device is selected in accordance with the icon display.