There is a Jacob Haybert listed in Lackenwald, West Prussia on the 1772/3 Land register. This is found at www.pixel.cs.vt.edu
There are the following on the 1776 Land Consignment (found at mmhs.org)
Jacob Hiebert of Klein Mausdorf (says he has no children LIVING with him, just him and his wife)
Jacob Hubert of Schonsee, his wife and a daughter, but no sons
I recall some years ago reading a footnote in a book that stated that David Hiebert, (1774-1852) a minister in South Russia, was indeed the son of Jacob Hiebert of Lackenwald... cant remember name of the book.
the above mentioned land documents only list those adult males who OWNED land, so there may be another Jacob Hiebert who did not own land....or the information about their sons is recorded inaccurately.