The present disclosure relates to a wearable input device, a host, an input method and an electronic system. The wearable input device includes a body, and further includes a detection module, a positioning module, a communication module and a processor which are provided on the body. The detection module is configured to detect whether the body performs a tap action on an operation plane, and send a detection result to the processor; the positioning module is configured to determine a current position of the body on the operation plane, and send the current position to the processor; and the processor is configured to send the current position or a key value calculated according to the current position to a host via the communication module when the body performs the tap action.