A method of controlling a wearable device, and which includes obtaining, by a camera of the wearable device, an image including at least a partial field of vision of a user; identifying, by a controller of the wearable device, an object appearing in the image obtained by the camera at a first time point; storing information about the identified object in a memory; detecting, via a microphone of the wearable device, a speech of a user using the wearable device at a second time point; identifying, via the controller, a word included in the detected speech of the user corresponds to the object identified in the image; retrieving, via the controller, the information about the object from the memory based on the identified word included in the detected speech; and outputting the retrieved information about the object.