import re

a = "sdfenacdsea"
print(re.search(r"\d*",a))

<re.Match object; span=(0, 0), match=''>

a = "23cadf32cdd"
print(re.search(r"[0-9]",a))

<re.Match object; span=(0, 1), match='2'>

print(re.search(r"(0-9)(3-8)","dsfwe232002321234566788"))

None

print(re.search(r'\d',"sdscw2"))

<re.Match object; span=(5, 6), match='2'>