I take my kids to the nearby high school track and they play while I run laps!
I’ve been doing this since my youngest was 2 1/2 and the older one was 5 1/2. Usually tracks have a long-jump pit and that’s where my kids hang out. To them it’s just a big sand box. Sometimes we bring dump trucks and buckets, sometimes old kitchen spoons, other times nothing at all. My kids love it! They sit in the dirt and dig while I run around and around and around. They know that they have to stay on the field inside the track (took a little bit of training the first few times). I can see them at all times and am never more than one minute away from them, but I am free to run without a jogging stroller. They actually ask me when we get to go to the track again. It is the perfect solution!
One note to consider: you may want to check with your local high school to find out the rules for their track.