You can get a location (latitude and longitude) of your form submitter, by just enabling geolocation option in Location field type.
You can collect GPS information from your users using Location field type with enabled Geolocation option.
Please, see below how to enable it.
Once enabled you'll see coordinates in your Location field in 'latitude, longitude' format.
Please, notice that getting location information may take up to 3 seconds.
Also it is not always returns 100% correct information. It may not return coordinates at all, because it depends from several factors, like network etc.
If you don't want to show Location field on your web form, but still want to collect GPS information, just hide field from form widget.
Even if geolocation field hidden from your widget, location data will be collected and you'll see the link to Google Maps on your Records page.
Please, notice, that having geolocation enabled you'll loose some form loading speed, i.e. adding new entry or opening web-form can take up to 3 seconds.