Compound Microscope was first used by:

Explanation

It had long been suspected that small creatures exist which are too small to be seen with the naked eye. However, their discovery was linked to the invention of the microscope. A Dutch Scientist "Antonie van Leeuwenhoek" (1673) was the first to report the microbes such as bacteria and protozoa. He used a simple microscope to describe bacteria and protozoa with accurate drawings and descriptions and called these small creatures as "animalcules". He first observed small creatures in rainwater and then confirmed these in saliva, vinegar, infusions, and other substances.