While many species of birds use bird houses for their home, the hummingbird does not do so. Therefore, you cannot purchase or build a bird house for a hummingbird. It is my hope that this post will help explain why hummingbirds do not use bird houses.
Hummingbirds are not cavity nesting birds. A hummingbird will make their small, cuplike nests in the fork of a tree branch. The nest is made of downey-like materials for their nesting like plant down, lichens, spider webs, etc.
A hummingbird nest is very tiny. It is difficult to describe just how tiny the nest is but I will try to give you some idea of its extremely small size. One source described the size of the nest as being about the size of a quarter. Another one described it as being about the size of half an English walnut shell. Either way, that is indeed very tiny.