Is it possible to capture the GPS location of PC that has my desktop app installed?
Desktop pcs do not have GPS sensors.
The best you can do is estimate the location based on the IP address.
Google these words:
geolocation from ip address api
Note however that any PC that is allocated its IP address using DHCP will have a local address. The external IP will be the same for all clients that obtain an IP address dynamically from a DHCP enabled router or wireless access point.