Pick mechanical engineering. Do CS courses on the side or get a CS minor.
The best way an engineer can make themselves marketable is by proving they have interdiciplinary intuition. Unless, you solely want to work in software, it’s useful to have practical hands on knowledge about a core branch of Engineering. In college, contribute to interdisciplinary student trams like Robotics, Hyperloop, SAE etc. Here you’ll truly understand how things are built and get a flavour of the beautiful intersection between CS and Mechanical Engineering.
Remember, you don’t chose at the outset that this is what you want to do. As a freshman with no background, it’s very difficult to make thus decision. The world is full of possibilities. The broader your background as an undergrad will be, better you’ll be able to grab them!
P.S Another exciting project between CS and Mech is Self Driving cars. Who says you can’t do both?