Before you begin, ensure you have access to both ClickHouse and Google Cloud. Install necessary tools like `clickhouse-client` for accessing ClickHouse and `gcloud` CLI for interacting with Google Cloud. Also, ensure Python is installed on your system for scripting purposes.

Use the `clickhouse-client` to run SQL queries and extract data. You can use a command like:
```bash
clickhouse-client --query="SELECT * FROM your_table" --format=JSON > data.json
```
This command exports data from ClickHouse to a JSON file. Adjust the query as necessary for your specific dataset.

Since Google Pub/Sub accepts messages in JSON format, ensure the data extracted is in the correct format. If necessary, write a Python script to parse and clean the data file:
```python
import json

with open('data.json', 'r') as file:
data = json.load(file)
# Process data if needed
```

Use the `gcloud` command-line tool to authenticate and configure access to your Google Cloud project:
```bash
gcloud auth login
gcloud config set project your_project_id
```
Ensure you have the necessary permissions to publish messages to Pub/Sub.

If you haven�t already created a Pub/Sub topic, do so with the following command:
```bash
gcloud pubsub topics create your-topic-name
```
This topic will be where you publish the data messages.

Create a Python script to read the JSON data and publish it to your Pub/Sub topic. Use the Google Cloud Pub/Sub client library:
```python
from google.cloud import pubsub_v1

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path('your_project_id', 'your-topic-name')

with open('data.json', 'r') as file:
data = json.load(file)
for record in data:
message = json.dumps(record).encode('utf-8')
publisher.publish(topic_path, data=message)
```

Run your script and monitor the process to ensure all messages are successfully published to Pub/Sub. You can do this by running the Python script:
```bash
python publish_to_pubsub.py
```
Check for any errors in the script execution and verify message delivery in the Google Cloud Console.

By following these steps, you will be able to move data from ClickHouse to Google Pub/Sub without relying on third-party connectors or integrations.