I would like to add a shower light, tapping off the existing exhaust fan in the room which is currently operated by a light switch. The goal is to have the fan and the light come on at the same time by switch, but be in 2 different locations. The light will be over the shower, the fan unit is on the other side of the room but I can access it through the ceiling and/or wall.

The exhaust fan is Broan, and the fan is connected behind the plastic vent by a 2 prong typical outlet built into the box, rather than being hard wired. The single outlet appears to be part of the unit's metal housing. The unit is probably 7 years old as is the house.

How can I tap into the wiring to the fan to add a light? The switch only controls the fan right now, and I want to be sure I get the light tied in to the right place so switch controls both. I've seen other postings where they've done it wrong, so any details on how to do it right would be great.

Thank you!

You need to get to the wiring connection box. That is where the house wires are connected to the fan. Unplug fan, take down fan and shroud. Usually one screw with opposite side held by tabs in slots of housing. Connect light wiring just like fan is connected.

Be sure to check the manufacturers instructions for the shower light, most if not all, require the fixture to be GFI protected if installed in or above a shower/tub.

Is this a ceiling fan or a recessed exhaust fan? TK is be correct in his warning but I'd go step further and ask your local building department what's their code. This seems to me to be an unusal arrangement but if its what you want then Tap into the box on the fan.