With the same Google Maps service. What you want is called 'reverse geolocation' .
Check out module PostalcodeHousenumber on a implementation is this functionality.
See https://userofpostalcodeho.mxapps.io/ for an online-demo of this module.
The Geolocation widget also does what you want.
Btw. Would love it if you would add the "using google maps so far is to using the Postcode and City to find the Geo Location" to this module. With your experience, this is probably a small task. The module is on Github. Thanks in advance.