Hi there need some help i drive a peugeot 206 1.4lx and theres a noise coming from undeerneath the bonnet?

wen driving the car will make a tick tick tick kiind of sound and pretty loud but wen i put my foot down on the clutch it seems not to b as loud i think i might b the gearbox but not sure because wen i reverse it doest make the noise its just normal it drives fine still to but really need to now wot it is so any help would be fantastic