There are a number of apps, with one of the most popular being “iNaturalist”. I you have a smartphone you can download and use the app. Citizen scientists use the app in the field to record observations of species all over the planet, and then scientist use the data to track those species. This data only reflects the observations of people who use the app, and who have taken time to enter their observations.
Here is the current observations of Rusty-patched bumble bees for southern Wisconsin:
Here are the observations from Middleton (airport is in the upper left):