There are 3 ways of catching mice.
The first way is sounding the horn.
Apparently other people have programmed some 'smart horns' known as auto horns, which sound the horn for you 24 hours. These kind of 'bots', 'scripts' and any automated form of playing the game are against the rules of the game and could get you banned from the game.
The second way are trap checks, that occur every hour. You only receive trap checks for the next 24 hours after you are offline. (Apparently hunters have a bad habit of checking their trap every hour and get tired after the next 24 hours.)
The third way is getting a friend to sound it for you. Not literally giving your friend your account email and password, when you are in the same location as your friend then when he sounds the horn his journal entry is the same as yours.