Checking for an anchor dragging by feeling the cable might work, but it’s not guaranteed. A compass bearing on a shore object can be ambiguous too, especially if the object is a long way off. The only sure-fire method is to see which way you’re going to drag, then find any two objects abeam of that ‘line up’ to form a natural transit. Anything at all will do. A bush and a hill-top, a house-end and a chimney, or even a gatepost and a cow chewing the cud, so long as she stays lying down!