Can I install a light switch/GFCI outlet combo?
This appears to be a switch loop. That is, a hot white coming down from a fixture to the switch and a black load wire going back to control a fixture. Since there is no neutral, you can't wire an outlet to the existing box with the existing wires. If you verify this to be true, put a few wraps of black tape over the white wire or mark it with a black magic marker to indicate that it's hot. You would have to replace the 14/2 with a 14/3 to bring the neutral down from the source to add the GFCI outlet.