Yea, we don't yet have support for harvesting from units, but this is discussed in another thread around here that hailstone replied to earlier, namely the "capturing", I suppose you mean building a "mine" on a "resource" like orcs do in warcraft or like the vespian gas in starcraft? As hailstone mentioned, adding locally stored resources and the ability to "garrison" units would take care of part of this, but we'll examine it more closely later when we get more of the core features fleshed out for 0.3