HUD Color Picker

In Photoshop CS5 and newer, you can use the HUD Color Picker. With the Brush Tool selected, hold Alt Shift Right-Click (Windows) or Ctrl Option Command Click (macOS).

To use the color wheel HUD Color Picker instead, press Ctrl K (Windows) or Command K (macOS) to open the Preferences window. From the General tab, select Color Wheel under the HUD Color Picker drop-down.

Then follow the keyboard combination described above to get the Wheel HUD Color Picker.