Basically, the hybrid attack is just a Combinator attack. One side is simply a dictionary, the other is the result of a Brute-Force attack. In other words, the full Brute-Force keyspace is either appended or prepended to each of the words from the dictionary. That's why it's called “hybrid”.

Alternatively you can use Mask attack or Rule-based attack to replace the Brute-Force side.

If your example.dict contains:

password
hello

The configuration:

$ ... -a 6 example.dict ?d?d?d?d

generates the following password candidates:

password0000
password0001
password0002
.
.
.
password9999
hello0000
hello0001
hello0002
.
.
.
hello9999

It also works on the opposite side!

The configuration:

$ ... -a 7 ?d?d?d?d example.dict

generates the following password candidates:

0000password
0001password
0002password
.
.
.
9999password
0000hello
0001hello
0002hello
.
.
.
9999hello

We can utilize the rule engine in hashcat to emulate the Hybrid attack.

This section has moved into a dedicated wiki page: Using rules to emulate hybrid attack.