First, post relevant security systems outside the gates and walls. Put up a propaganda slogan "Stealing secrets will be caught".

Second, the magic is one foot high and one foot high. The troops should also be equipped with anti-sneak shots, such as drones with better performance and greater power. Once a drone is found to take a sneak shot, it will immediately dispatch its own drone to find the operator. Or just shoot it down. Investigation controller, hell to pay.