There's not one in any typical cockpit I can think of, although it is a parameter stored on the flight data recorder.
The attitude indicator that you refer to is the best instrument for avoiding spatial disorientation. That is, even if the pilot is in thick cloud or with G forces trying to fool their body into thinking they're rapidly climbing, the pilot simply looks at this instrument which has a visual representation of whether the aircraft is pointing up or down, in a banked turn or level. In instrument flying, the pilot is continually scanning between the bank and pitch indications to keep the plane doing what they want it to be doing.
Replacing this instrument with a series of numbers to interpret is a big step backwards in safety, for the simple reason that pilots are not computers. Pilots are susceptible to human errors and in times of stress need information presented to them in the simplest manner possible. Having to think "wait does that number mean my bank angle 20 degrees to the left or to the right?" is easy enough in isolation, but combine that with every other activity they've got on and you will end up with fatalities at some point.
I don't think it would be too hard to add a digital readout in addition to the attitude indicator, but there's not really any benefit. The existing instrument is easy enough to read within a degree or two, which is accurate enough for all actions. I've never met a pilot who can hold an attitude to a tolerance of less than a degree anyway.