1. A method for early warning of danger, performed by a wearable device, the method comprising: acquiring, by an image sensor of the wearable device, image information of a target object; acquiring, by an audio sensor of the wearable device, audio information of a surrounding environment; detecting a physical characteristic of the target object based on the acquired image information; detecting an audio characteristic of the target object by separating the audio characteristic from a background sound based on the acquired audio information; determining a degree of danger that is a degree to which safety of a user is endangered, by using the detected physical characteristic and the audio characteristic; and providing a warning to the user based on the determined degree of danger.