an image capturing device, configured to capture a plurality of real-time images including at least one wearable device worn on at least one finger position of a user; and

a processor, coupled to the image capturing device, configured to:

generate a wearing position distribution based on the real-time images, wherein the wearing position distribution indicates a wearing position of the at least one wearable device worn by the user;

receive a pairing request;

establish a communication connection with the at least one wearable device in response to the pairing request;

calculate a pairing quantity of the at least one wearable device having the communication connection with the head-mounted display; and

compare a wearing quantity corresponding to the wearing position distribution with the pairing quantity to generate an unlocking signal to unlock the head-mounted display based on the wearing position distribution.