Hilchos Ishus 5:17
Let’s say that the man is owed money by a third party and he tells the woman in front of this third party that she is consecrated to him by him transferring to her the debt that he is owed. In such a case, marriage is effected.
Hilchos Ishus 5:18
Let’s say that a man consecrates a woman by giving her an object that he has already lent to her or left with her for safekeeping. If the item in question is worth at least a prutah and is still in her possession, then marriage is effected.