Pass Column Object into UDF Scala

Question

Here is my code block., I want to pass Column to "calculateCredit" but the following code GlobalLock take value of that column.

object CreditHostory {

    def calculateCredit(rows: Row)  = {

    }

    def main(args: Array[String]): Unit = {
    sparkSession.udf.register("calcCredit", calculateCredit _)

    callUDF("calcCredit", struct(col("credit") , col("amount")))
    }
}