In Photoshop CS6, you can set the Color Sampler readout to HSB so sampled points show hue, saturation, and brightness instead of only RGB. That’s the simplest way to read an individual pixel’s brightness and hue directly.

Be cautious about relying on published RGB values from a color checker card. Those reference values can vary, and many are based on D50 viewing conditions, so they may not match your capture lighting or camera response well.

If you need consistent, repeatable color accuracy, the better approach is to control your lighting and white balance, then profile your camera/setup with a proper calibration target and profiling software. That gives you a standard color profile and makes your images more comparable than trying to force card patches to fixed RGB numbers manually.

So: use HSB readouts for measuring hue/brightness, and use profiling rather than card RGB values if your goal is accurate color measurement.