circle = Disk[{4.5, 3}, 0.5];
pin = Rectangle[{4, 0}, {5, 3}];
square = Rectangle[{0, 0}, {9, 9}];
region = RegionDifference[square, RegionUnion[circle, pin]];

sol = NDSolveValue[{D[u[x, y], x, x] + D[u[x, y], y, y] == 0,
bc},
   u, {x, y} [Element] region]

DensityPlot[sol[x, y], {x, y} [Element] region, Mesh -> None,
 ColorFunction -> "Rainbow", PlotRange -> All,
 PlotLegends -> Automatic]