Mix chickpeas, olive oil, apple cider vinegar, and salt in a shallow baking dish (shallow so that the liquid can soak more of the chickpeas). Set in refrigerator to marinate for 4 hours or overnight. (If not marinating, mix in a bowl.).
After marinating, stir chickpeas with all other ingredients (except for feta) in a bowl.
Just before serving, sprinkle crumbled feta over the salad.