Rhabdomancy
Dowsing (Greek rhabdos, rod) is divination by using a rod or pendulum to find water, hidden objects, treasures or energy fields. Variant of radiesthesia. The famous "dowser" with forked rod (Y-shaped) is a popular cultural image since the Renaissance.
Tools
Y-shaped forked rod (traditional), L-shaped rod (metal, modern), pendulum. The "movement" is the ideomotor effect.