Placing fencepost close to house?
If you can use the strength of your wall, it will be quite strong to butt against the house, I would dig up to the cement foundations, then butt your post against the wall. About 3/4 the way up, just fix the post to the wall. (if the wall is cement you can use a rawl bolt, otherwise a nice threaded bolt will do the trick. You will not need anything too over the top, since the forces will mostly be from side to side (i.e there will not be too many pull forces that would pull the pin out. 
If you would like more specifics, you would need to elaborate the shape and material of the post as well as the wall.