How can I ensure that Excel can import my pip-installed python libraries?

I have a script that imports Selenium WebDriver and it runs fine in VisualStudio debugger but fails when I call it from an Excel module because it can't find the Selenium module. Here's the code stub:

from bs4 import BeautifulSoup
import sys
import csv
from selenium import webdriver
quit()

If I comment out the selenium import line it runs when I call it from Excel. I assume these are running in different environments. I installed Selenium via pip in a terminal window which made it available to the debugger but not to whatever runs when I call it from Excel. Any ideas about how to check and fix this?