In this article, we present an experimental study on probing conducting particles buried in a Ni-x(SiO2)(1-x) composite with x around the percolation threshold x(c) by conducting atomic force microscopy (C-AFM). The buried conducting particles were "observed" via the electric current image of C-AFM at constant bias. The current from buried conducting particles originates from held assisted tunneling through the insulating layer. Examples of measuring the thickness of the insulating layer will be given. The analysis shows that it is possible to probe the buried metal particles as deep as several nanometers underneath the surface. By correlating the surface topographic and the current image, the profile of the metal-insulator interface can be measured. General issues on spatial resolution will also be discussed in this article.