every possible combination of the contents of 2 columns in excel

Suppose I have 2 Columns:

1st column(contains 1000 rows):

U-0001

U-0002 

2nd column(contains 10 rows):

B01

B02

B03

Now, I want to generate two columns like this(with 10*1000 = 10000 rows):

U-0001 B01

U-0001 B02

U-0001 B03

U-0002 B01

U-0002 B02

U-0002 B03