You have to apply to an MD – PhD program.

You should have an academic advisor who can lay out the details for you.

@janbb Actually you don’t need a PhD to be a physician scientist. Plenty of physician scientists have just an MD.

First, become a physician. That means going to med school. Then, when you get your MD, seek jobs doing research. Or apply for grants to fund doing research on something you think is worthwhile and could prove of value in furthering understanding on a matter.