Assuming you have adb
installed in your OS, your Android phone is connected to it via USB, debugging is enabled, and you can see your phone running adb devices
.
Open your terminal and run:
adb shell pm list packages |grep AppName
This will show you something like package:/path/to/your/app.apk
Without |grep AppName
or the search filter you use it will list all installed Apps.
Finally, just run:
adb pull /path/to/your/app.apk path/to/desired/destination