The best way to clean your caps is to hand-wash them instead of placing them in a washing machine. This will help with retaining their shape and won't diminish the quality of the embroidered design.
We recommend you wash them with a mild detergent (not bleach), in lukewarm water. If there are any spots that require more attention, you can use a damp cloth, but don't use brushes.
You can also check with the manufacturer directly or search YouTube for other recommendations.