Measuring ripple voltage using on-board components. Is it possible?
Well duplicated here and on the web are imperfect desires for low noise with no specs on: signal {V,I,Z, BW} or Noise {...}. The answers do not depend so much on choice of PS , rather an understanding that noise ingress into high Z signals can be induced by every mode; conducted , radiated, common mode impedance ratio from source that converts to differential noise. 

The answers are everywhere, Baluns, twisted pairs shielding, CM chokes. Pi filters , Cable orientation and proximity , decoupling caps. Each of many solutions depends on specs (a priori)

The expertise and wisdom  comes from simple impedance divider relations from source to destinations using CM Impedance., Zcm and differential Impedance Zdm, from unbalanced lines. CM chokes serve to raise Zcm over some limited spectrum to create more balance and greater attenuation.  Twisted pairs and shielding serves to lower Zdm(f ) from stray coupling either pF from 240Vac rms E fields or nH from current nearby induced power cords.

You will need many articles or a good book (Henry Ott) on EMC, EMI reduction, to fully comprehend.