There isn't a widely known 'fiction book' by Merleau Ponty in the typical sense. His works are more in the realm of philosophy. But if we stretch the definition, his works like 'Phenomenology of Perception' can be thought of as having elements that are similar to fictional exploration. It uses examples and descriptions that are somewhat like the fabric of a fictional world, but all in the service of exploring deep philosophical concepts related to human perception and existence.
Merleau Ponty is mainly known for his philosophical works, but some of his essays and philosophical treatises can be read in a way that has fictional undertones. For example, his exploration of the body - subject relationship can be seen as creating a kind of fictional world of perception and experience. However, he doesn't have traditional 'fiction books' in the pure sense. But if you consider works that use creative and narrative - like approaches to philosophy, his works are worth exploring.
One of Merleau Ponty's notable works that has fictional elements is 'The Visible and the Invisible'. It delves into complex philosophical ideas through a unique narrative style that can be seen as having a fictional quality in how it presents and explores concepts.