Check if there are any string values in whole dataframe

I am trying to apply Zscore function on my dataframe like this:

x_columns = df.columns.drop('Label')
for col in x_columns:
    df[col] = zscore(df[col])

and i had got this error:

TypeError: unsupported operand type(s) for +: 'float' and 'str'

I understand that there are string values in my dataframe Although i made the data cleaning on all columns

Is there an easy way to check if there are any string values and where they are located in my dataframe???