chose and tracking object.

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You can try "Real-time compressive tracking" [1]. It does what you want. You can at least try it. Project page PDF It includes C++ code ready for test with your webcam; you select a initial tracking box and the tracker tries to track it.

[1] Zhang, K., Zhang, L., & Yang, M. H. (2012). Real-time compressive tracking. In Computer Vision–ECCV 2012 (pp. 864-877). Springer Berlin Heidelberg.

You may want to try Good Features to Track and search the neighborhood of the click-location for features, choose one and track it.

In case you know the shape of the object that is clicked (and you have some descriptors of an object detection algorithm for it already) you can first check if the correct object was clicked and then track it.