It is not exactly clear how the lot worked. Perhaps something was thrown on the ground, and depending on which way it landed, that would determine whether or not someone was chosen
by the Lord. According to Proverbs 16:33, casting lots is under the direction of the Lord. The Lord’s hand will guide the lot to identify the guilty party.
14 In the morning therefore you shall be brought near by your tribes. And the tribe that the LORD takes by lot shall come near by clans. And the clan that the LORD takes shall come near by households. And the household that the LORD takes shall come near man by man.