Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics:
A compound microscope consists of two convex lenses coaxially separated by some distance. The lens nearer to the object is called the objective. The lens through which the final image viewed is called the eyepiece.
Object is placed beyond first focus of objective which formed inverted image(magnified). This acts as virtual object for eyepiece. This virtual object lies between focus and optical centre of the eyepiece and eyepiece acts like simple microscope and form a virtual erect and magnified final image.