There are competing theories about the Constitution being a compact or not.

It is the opinion of courts that the Constitution is not a compact, but the majority of the authors of the Federalist Papers refer to the Constitution as a compact.

A compact refers more to the founding document of a confederation such as the Articles of Confederation.

According to Wikipedia, the States were the creators of the Articles of Confederation.
The People of the United States are the creators of the Constitution.

Compact theory