You can do a fairly simple exponential filter to eliminate high freq noise, or a rolling average filter is pretty good

The expression you are trying to build is
Xn=k D +(1-k) Xn-1

Where K<1, D is the latest data point and Xn is the latest filter output

Experimen twith K to suit your ADC process. And bear in mind that "noise" might be because your signal is too low level for the rangeof your ADC.

Steve