library(shiny)
ui <- fluidPage(
  actionButton(inputId = "dummy_button", label = "This is a button"),
  verbatimTextOutput(outputId = "detector"),
  tags$script('
              var counter = 0;
              var ctrlDown = false,
              ctrlKey = 17,
              cKey = 67;
              $(document).keydown(function(e) {
              if (e.keyCode == ctrlKey ) ctrlDown = true;
              }).keyup(function(e) {
              if (e.keyCode == ctrlKey ) {
                ctrlDown = false;
                counter = counter + 1
               Shiny.onInputChange("mydata",counter );
              }

              });
              ')
  )



server <- function(input, output,session) {

  counter <- reactiveVal(0)

  observeEvent(input$mydata,{
    counter(counter() + 1)

  })

  output$detector <- renderPrint({
    req(input$mydata)
    paste("button clicked", counter(), "times")
  })

}

# Run the application
shinyApp(ui = ui, server = server)