Rhabdomancers do it by using the practice of dowsing, which is a technique used to locate underground water, minerals, or other hidden objects. It involves using a forked stick, rod, pendulum, or other tool to search for the object. The tool is held in the hands of the practitioner and moved over the ground until it reacts to the presence of the object. This reaction can be a slight movement of the tool or a change in the direction of the tool. Dowsing has been used for centuries and is still practiced today.