Our aim is to provide a construction of the decoration point measure appearing in the extremal process of the branching Brownian motion, by constructing the law of this process seen from its topmost particle. This construction involves the law of a Brownian motion penalized by a solution of the F-KPP equation. We therefore give a general description of the law of a Brownian motion penalized by a time-inhomogeneous potential, which is of independent interest. This is joint work with Bastien Mallein (Toulouse).