They can drink from water droplets misted on the wall, yes, but they need food as well.
For the really tiny ones, if I can't find pinhead crickets, I cut up little meal worms, or offer a cricket "drumstick" (large back leg).
A word of warning about water and tiny slings. I once had a C. elegans spiderling that was shipped to me in an empty pill vial. After unpacking it, I spritzed a little water on the side of the vial. The misted water ran down, forming a large drop, that drowned the spiderling. If I'd taken the extra two minutes to put in a pinch of substrate, the water would have been absorbed. A tragic lesson I learned in the hardest way.