They'd be notified that someone looked it up unless you buy the entire full set of data for the entire county / country, as it contains a bunch of people all together then. Also, in the notification they receive, only which service was used will be mentioned and not exactly who did it.
So you can still lookup how much your co-workers earn without them knowing you asked for. But generally people are open with how much they earn, so it's really not an issue.