The simulators are located under:
~/Library/Developer/CoreSimulator/
Here, they are listed as directories with UUID names. Use sort by 'Date modified' to find the latest one. Inside navigate to:
/data/Containers/Data/Application/
Here you will get a list of all the applications on that device. You can again sort this to get the latest app.
NOTE: Xcode changes the directory name every time you run the app, so don't rely on making alias/short cuts on desktop.
The easiest way is to use the app here, which does everything automatically.