library('caret')

fitControl <- trainControl(
  method = 'LOOCV',                # k-fold cross validation 'cv'
  number = 1,                     # number of folds
  savePredictions = 'final',       # saves predictions for optimal tuning parameter
  classProbs = T ,                 # should class probabilities be returned
  summaryFunction=twoClassSummary  # results summary function
) 

train(Species ~ Sepal.Length, data=irisData ,method='rf',   tuneGrid=data.frame(mtry=1)  ,trControl = fitControl)