The parish birth, marriage, and death records almost always identified the individual persons as being either peasants, townspeople (burghers) or "noble" (and there were sometimes titles implying higher degrees of nobility). If one of your ancestors was "noble", there might be a "nobility document" that shows the male ancestors of that "noble" ancestor. [These generally go back farther in time than the Roman Catholic parish registers.] In general, these documents are located at LVIA (the Lithuanian State Historical Archives) and are not online, so they must be obtained via either LVIA or by a private professional professional researcher who has experience searching for nobility documents at LVIA.
Refer to the following examples of nobility documents: