As mentioned in title, is there any direct or another way around to do so? The closest way I got is to equip the excess Stimpack and Radaway to dweller who is traveling to wasteland.
As far as I know, that's the only way to get caps from Stimpacks and Radaways. If you have too many of them, just remove some workers from the two producing rooms (Science Lab and Medbay) and put them in other rooms.
Independent of how full your stock is, you'll still get caps for collecting more, but equipping them to wastelanders is the intended action.