Don't forget to film this happening, repeatedly.
If you can show it's much more than a one-off, and how low the drone is, etc., you may get a more sympathetic reaction from authorities. Whether it's the police, a court, or whatever.
In addition to drone use and behavior, specifically, many communities have nuisance laws and ordinances.
If your neighbor is making a nuisance of themself, the "drone" part may be incidental in getting the behavior to stop.
Best wishes.
P.S. For example, you may have a perfect right to use a leaf blower on your yard. But if you are compulsive with it and spend 2 - 3 hours every day blowing every last speck off your lawn and driveway, you may be found to be a nuisance.