Simple non-Hamiltonian systems with an invariant measure

We propose a simple construction of the non-Hamiltonian dynamical systems possessing an invariant measure. These non-Hamiltonian systems are deformations of the Hamiltonian systems associated with trivial deformations of the canonical Poisson brackets and time transformation. Sometimes these non-Hamiltonian systems can be identified with known nonholonomic systems and, therefore, the results are illustrated through the Chaplygin ball and the Veselova system.