Politicians and their campaign teams have long targeted voters and potential donors by combing through things like public property records and voter registrations to find out how often you vote, what your home is worth and what party you are aligned with.

But now they're able to learn even more about you.

By buying reports from data brokers that track your purchases, web surfing habits and social media activity, political candidates can now figure out the issues you support, how much money you earn and the best way to reach you.

"(Big Data) tells us who they are, where they are, how old they are, what they like on Facebook, what they talk about online—and what they dislike," explained Jake Rosen, a Fleishman-Hlllard strategist, in a 2012 report about campaign use of data analytics.

The problem is that many Americans have no idea that they're being profiled, said Jeffrey Chester, executive director of the Center for Digital Democracy.

"Not only do you have no idea, but you have no way to control that process whatsoever," he said.

Related: Big Data is secretly scoring you