How to make normal/height map from grayscale texture?

I have a grayscale RGB image that I’m using to texture a material, and I’d like to use it to affect the normals also.

I see there’s a normals from heightmap node, but it won’t accept an RGB, float, or appended floats. How can I use the grayscale image as a bumpmap?

texture object → normalfromheightmap