I suggest you look at the research by persons examining Mindfulness Based Cognitive Therapy, Acceptance and Commitment Therapy, and Dialectical Behavior Therapy (along with the older work of Jon Kabat-Zinn). I think you will find instruments in their research suitable to your needs.
Thanks for your answer. I have used MAAS. But I am looking for some sort of scientific actual measurements similar to answers of Richard E Watts and Hong Yu.