Dear Sileshi, the implementation of CMAM is particular for each zone, therefore there would not be a tool applicable to all zones; However, UNICEF has already carried out evaluations of the impact of this intervention in several countries, which you can check on this link or on the UNICEF website.
Keep in mind that to raise the question of the impact evaluation and indicators it is necessary to identify the theory of change or the logical model of intervention, this is what can change from one scenario to another and make the intervention particular.