You can use triple backticks ``` to mark code blocks ():

```
This will be monospaced
```

Renders as:

This will be monospaced

To be interpreted correctly, the three backticks need to be at the start of the line and immediately followed by a line-break.

Be aware that any preceding paragraph content should be properly terminated with a double line break, too. So, this example is wrong:

This is an ordinary paragraph
```
This will be monospaced
```

The correct version is:

This is an ordinary paragraph

```
This will be monospaced
```

Note that some keyboard layouts treat the backtick as a dead key, making it hard to type. The trick is to type three backticks followed by a space. Alternatively, type all six backticks in one go, then a space, and then move the cursor back three characters to type or paste the content.