The best way for you to get targeted mortgage lead within a specific area is to run a PPC campaign on Google ads.
In the United States, this accounts for a large chunk of the location-specific Google ads for certain services.
Depending on how big the metropolitan area is, you can still get away with fairly affordable PPC rates.
But good luck doing that in more competitive MSAs like Los Angeles, New York, or the greater San Francisco Bay Area.
But if you're looking for mortgage leads, your best bet is PPC.
I'm sure you can also do this with Facebook ads, but you probably would have to do a lookalike campaign.
So maybe run a content campaign first to profile the interest of the typical person that would end up on a lead collection page, and then run a lookalike campaign.