3 yr old running off

Any tips n tricks to keep them from running off away from you while out (usually parks or out on walks but stores occasionally)? When she decides to do it she doesn’t care about any discipline until after it happens and chasing her with a new baby is the worst. It’s not all the time but it scares me when she does it because she’s fast and I worry about losing sight of her or not being able to catch her fast enough since I’m holding a baby