I guess this is fairly simple, if the sensor output is something between 0V and 5V, then a voltage divider in front of the Analog input pin will do the job.
Where Vout = R2/(R1 + R2) Vin.
Vin max = 5V and Vout max = 3.3V. I think it's a good choice to select R2 around 10KOhms.
When a sensor output is digital 0 (0V) or 1 (+5V) a logic level shifter is the solution to level shift to 3.3V