Use lavender: either a bundle of dried flowers in a cloth bag, or some lavender essential oil dropped on a little felt pad (put not touching the wool).
Bay leaves can also be added as their scent also repels bugs.
Place your wool in strong, hermetic plastic bags if needed, with the lavender/bay leaves, especially when you store them away during summertime.
If the presence of moth is confirmed, place your clothes in a freezer for a few days before cleaning them and putting them back in your drawer.