Assuming your existing column is character data type, and your new column with a formula is numeric, you can set the column formula for the new numeric column to be: try(num(:col)) where col is the column name. This seems to work without the try statement, so I suppose you can just use num(:col).
See examples below. The first removes everything but integers. The second allows for decimal numbers (assuming period as delimiter).
Formatted numerics such as dates or scientific notation require a little more complex search string.
num(Regex(pi, "[^0-9]+", "", Globalreplace));
num(Regex(pi, "[^0-9.]+", "", Globalreplace));
Edit: just learned this has posted before. See Craige's excellent post in this thread Extract numbers from string in JSL