Leave your planned itinerary with someone you trust. A photocopy of a map with your planned route highlighted is best. If you are considering some side-hikes, include that info too ("We MAY explore this side trail if time allows"). Add to the map your planned times and other important details. When you expect to leave the trailhead, arrive at the cave, return to the trailhead, the license number of your car, who you are hiking with, etc. Maybe even a list of the gear you are carrying so they can estimate your level of preparedness. Make sure your trusted person knows who to call (rescue group - include contact info) and how soon after you're overdue to call them.