To cite caret in publications use:

Kuhn, Max (2008). “Building Predictive Models in R Using the caret Package.” Journal of Statistical Software, 28(5), 1–26. doi:10.18637/jss.v028.i05, https://www.jstatsoft.org/index.php/jss/article/view/v028i05.

Corresponding BibTeX entry:

  @Article{,
    title = {Building Predictive Models in R Using the caret Package},
    volume = {28},
    url =
      {https://www.jstatsoft.org/index.php/jss/article/view/v028i05},
    doi = {10.18637/jss.v028.i05},
    number = {5},
    journal = {Journal of Statistical Software},
    author = {{Kuhn} and {Max}},
    year = {2008},
    pages = {1–26},
  }