do you know which area the noise is coming from?

Those areas include engine bay area (could be further determined as in front, rear or bottom of engine, by lifting up the hood and listen; sometimes you can use a stethoscope); bottom of car (could be transmission mount or axle shaft if your car is a rear wheel drive) or rear (drive axle, differential for RWD)...

Also you'd need to tell when the noise exists - during moving (driven) or just in parking and idling...

If it's parking/idling, depends on what car it is, it could be belt loose, or any one of aux bearings (tensioner, alternator, AC compressor or water pump)...

good luck.